OK so what I want is a way to pressurise a ball so much that when I serve it just explodes. Must be a way.

Don't say I didn't warn you, but yes. There is a way and it can still go off in your hand. You will loose lots of balls trying to get just the right pressure, too. You will need a tank that will go high enough to charge the balls with enough pressure to explode. Yes the stainless steal tanks. Stay with all new ball, same make, model and production run. Over charge them. Start at say 50 PSI for a week. When you open the tank, if one does not explode right away, put it back in. Charge to 60PSI. Do this ever 10 PSI till the first one pops, explodes or pfisses out. Then take your balls out, in a black ball bag to increase the pressure in the sun. Gently set them next to you, and pull them out one at a time. Serve.

The idea is that they are right at the limit of bursting, the hot sun will increase it further. The sudden impact will burst them..... Ever hold a balloon in your hand and it hurt when it popped? 100 times that, so it will hurt. Damage to your racket, use an old one that needs restrung.